Methylisothiazolinone
Preservative
Methylisothiazolinone is a chemical used to prevent the growth of bacteria and mold in products like cosmetics, cleaning supplies, and paints. It's often used in combination with other preservatives to keep products fresh and safe to use.
Source: EWG Skin Deep
Methylisothiazolinone has been linked to skin irritation and allergic reactions in some people, which is why it's considered a high concern ingredient.
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Effects of slime toy poisoning in children and teenagers.
de Oliveira MJS, Bezerra MVF, Loiola RA
2022
Read on PubMedpreservative free skincare products for sensitive skin
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Last updated: May 16, 2026